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TRINA DAS

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· 1 Months ago

Detailed solution gives answer as option C but correct one is marked as option B.

Question:

     The inner circumference of a circular race track 7 m wide is 440 m. Find the radius of the outer circle.

Options:
A)

      57m

B)

      68m

C)

      77m

D)

      69m

Solution:

  

width of the circular race track = 7m

Let inner radius of circular race track = r metre

(R)  outer radius = ( r + 7 ) m

according to the question

2πr    = 440       2×227×r     = 440, r = 70m

outer radius = ( 70 + 7 )  = 77cm 

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